Are Tortoise Recovery Actions Effective?

1
Are Tortoise Recovery Actions Effective?

• William I . Boarman
• USGS, WERC
• Conservation Science Research Consulting
• William B. Kristan, III
• CSU, San Marcos
• Ed LaRue
• BLM
• Circle Mountain Biological Consultants
• Paul Burgess
• Redlands Institute

2
Supporters

• Marine Corps (MCAGCC)
• National Park Service (MNP)
• US Fish and Wildlife Service (Ventura)
• Bureau of Land Management (CDD)

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Goal/Objectives

• Goal Evaluate the state of knowledge about
  effectiveness of tortoise recovery actions.
• Objective1 Gather and critically evaluate best
  available evidence.
• Objective 2 Map the extent of effrorts to
  monitor recovery actions.

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Questions
How much information is available to support
recovery actions, and what kind of information is
it?
Is the effectiveness of recovery actions well
supported by scientific evidence?
How can tortoise management be improved?
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Caveats

• Evidence of threat ? effective recovery
• Absence of evidence ? evidence of absence
• No new data analyses
• Focused on California

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Data Squeeze

• BLM
• Barstow
• Moreno Valley
• Needles
• Ridgecrest
• Sacramento
• State Parks
• Red Rock Canyon
• USGS
• San Diego

• FWS
• Ventura
• Barstow
• Carlsbad
• NPS
• JTNP
• DOD
• MCAGCC
• China Lake NAWS
• Fort Irwin

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Based Evaluation on Several Criteria

• Individual vs. population
• Project vs. action-level
• Study design
• Source of information
• Certainty of recovery

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Results

• 395 documents found
• 107 were relevant
• 44 were designed studies
• 107 were other types of information

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Limit OHV Access
Monitored before and after controlled
races Some success demonstrated Some failures
demonstrated Evaluations were too
subjective Network reductions Routes/tracks
proliferated, but less than outside Little
evidence of effect on diffuse problems
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Limit OHV Access
Vertical mulching Claimed to work, but no
studies. Needs Effect of OHV removals on
tortoise populations, weeds, and
habitat. Effect of OHV reductions. How much
degradation can tortoises withstand? OHV means
many things
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Restrict or Eliminate Grazing
Some exclosure studies Improvements noted
Level of impact varies with distance from
water source Needs Threshold stocking levels
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Road Mortality and Barrier Fencing
Moderately well studied 89 reduction in road
kills Use culverts Different materials
tested Needs Population-level
effect Bycatch rate Culvert design spacing
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Other Actions We Could Evaluate

• Reserves
• Construction
• Habitat Restoration
• Translocation
• Predator Management

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Actions We Could not Evaluate

• Burros
• Habitat Loss
• Habitat degradation
• Disease
• Control of Invasives
• Drought

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Conclusions

• Few studies designed to evaluate effectiveness of
  recovery actions.
• Many lost opportunities
• Managers must often rely on non-scientific
  information

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Recommendations

• Coordinate monitoring activities
• Conduct studies to assess population responses
• Managers and Stakeholders find the funds and
  obtain scientific advice on design,
  implementation, and interpretation
• Scientists develop and seek funding for
  effectiveness studies
• Publish results